Civil engineering material and construction method of the same

ABSTRACT

The invention aims to provide a civil engineering material effective to suppress heat island phenomenon in urban cities, develop environments matching with the ambient environments of a construction site, and carry out greening of a desert as well as excellent in washing out resistance and/or planting suitability depending on the objects (or purposes) of the civil engineering works and to provide a construction method of the material. The civil engineering material comprises 10 to 40% by weight of water on the basis of extrapolation amount added to a mixture, which includes 0.5 to 10.0% by weight of cement and 90.0 to 99.5% by weight of an aggregate powder containing fine powder with 0.1 mm size or smaller in 10 to less than 50% by weight. In this case, a coloring material and seeds of plants may be previously added.

TECHNICAL FIELD

The invention relates to a civil engineering material and a constructionmethod of the material, more particularly to a civil engineeringmaterial usable for soil amendments for paddy fields as well as landsliding prevention materials in a side walls (finished face) of roadspassing along slopes and steep slopes in the ruins of quarries, roadbedmaterials in flat ground, paving materials, and surface materials andafforestation materials for parking lots, parks, and sports fields suchas ball game stadiums, foot ball fields, and the like and a constructionmethod of the civil engineering material.

BACKGROUND ART

The applicant of the invention previously presented a paving material inJapanese Patent No. 3,080,288 that has resistance to washing out andland-sliding (the property to stand against flowing out by rain water)even if it is used for construction of finished faces of such as steepslopes in the ruins of quarries, roads, and flat ground just like parksand that enables planting and its construction method. Specifically, theapplicant previously presented a paving material including 20-40% byweight of water based on 100% by weight of cement-mixed aggregate powderwhich comprises 0.5-10.0% by weight of cement and 90.0-99.5% by weightof aggregate powder including more than 50% by weight of fine powder 0.1mm or less in size. The construction method of the material involvescuring the foregoing paving material, which is kneaded by a kneader, for2 to 3 days; and then, loosening the aggregates of the paving materialby shifting it to another place at least once; and again curing thematerial.

The paving material (hereinafter, referred to as Hosolite) is providedwith resistance to washing out and land sliding and at the same timeplanting suitability (easiness to grow plants) and is developed becauseit enables recycling of the excavated soil generated in an excavationfield as an aggregate and thus allows economical construction of roads,repairing works for land-slid sites, and parking lot construction.Accordingly, the fine powder size and the content of the aggregatecomposing the Hosolite and the addition amount of water are determinedbased on the above-mentioned applications. The strength between cementconcrete and soil was found in Hosolite and places constructed using aconstruction method of Hosolite such as the finished faces of steepslope walls in the ruins of quarries, roads, and flat ground just likeparks. Therefore Hosolite is expected to be sufficiently useful forenvironmental preservation and disaster prevention.

However, the recent social situation has been changed drastically fromthose years the Japanese Patent No. 3,080,288 was filed and especiallyin terms of the living environments, further strict improvements havebeen required. To say more particularly, it has been an urgent issue tosuppress greenhouse effects attributed to CO₂ increase in atmosphericair and heat-island phenomenon in urban cities (the phenomenon in whichheat is stored especially in summer and cities become just like hightemperature islands since they are composed of civil engineeringmaterials such as concrete, asphalt and the like). Therefore, even if itcosts much to deal with such problems, it is desired to providerevegetation on roof and make roads and open ground excellent in thewater permeability (easiness of water permeation) and water retentionproperty (easiness of water retention).

On the other hand, there are sites just like parking lots where higherwear resistance is more desired than planting suitability in cities. Insuch sites, it is desired to use a civil engineering material that issuitable for generating no powder dust even if it is abraded byautomobiles or the like and excellent in ventilation, waterpermeability, water retention property, washing out resistance, andthermal conductivity rather even if it does not have plantingsuitability and such sites are constructed using the civil engineeringmaterial useful for preventing the above-mentioned heat islandphenomenon. Also, as illustrated in FIG. 2, it was previously desiredthat the lower part (about 2 m lower range along the finished face) of aside wall (the finished face) of a road developed by cutting out a slopeshould have plantability, however in these years, non-plantingsuitability is preferred in terms of elimination of mowing work,prevention of plants from obstructing traffic, or prevention of firingin mountain. Moreover, since the appearance is not good if the concreteis used, it is desired for such a part to have color well matching withthe ambient environments. Also, it is desirable to re-use the debrisflow for the aggregate of Hosolite in a site where the debris flowoccurs, however in the case of the conventional Hosolite, there is aproblem that the fine powder contained in the aggregate has too largeparticle size and therefore, the repairing work cannot be carried out asdesired.

In addition, as a series of countermeasures against recent globalwarming, there is an issue of greening a desert and presently, mainlynursery trees and trees are planted in dug out holes in a desert.However, the soil of the desert has good water permeability but no waterretention capability. Also, in terms of the weathering condition, notonly the water evaporation is high but also the embedded soil is blownout by strong wind and the roots of plants are exposed to the surfaceand thus the nursery plants and plants can hardly grow in the presentsituation.

In such a situation, the invention aims to provide a civil engineeringmaterial that not only has excellent washing out resistance and/orplanting suitability but also is effective for suppressing heat islandphenomenon in urban cities and for producing environments matching withthe surrounding of a work site and carrying out greening of a desertdepending on the object (or the purpose) of the civil engineering workand to provide a construction method using the material.

DISCLOSURE OF THE INVENTION

In view of the above circumstances, the inventor has reviewed the pavingmaterial and its construction method disclosed in Japanese Patent No.3,080,288 and has embodied resulting outcome in the present invention.

The present invention provides a civil engineering material comprising10 to 40% by weight of water on the basis of extrapolation amount addedto a mixture, which comprises 0.5 to 10.0% by weight of cement and 90.0to 99.5% by weight of an aggregate powder including 10 to less than 50%by weight of fine powder with 0.1 mm or smaller in size. In this case,it is preferable to mix one or more types selected from iron oxide,granulated blast slag, steel refining slag and artificial coloringmaterials all in form of granules with the mixture. Or it may bepreferable to mix seeds of plants and/or fertilizers with the mixture.

The present invention also provides a construction method of the civilengineering material comprising the steps of;

kneading the civil engineering material; curing the material for 8 to 48hours; loosening the agglomerates of the hardened material at leastonce; and curing again the material by applying a prescribed pressure ata working site.

The present invention further provides a construction method of thecivil engineering material comprising the steps of; kneading the civilengineering material; curing the material for 8 to 48 hours; looseningthe agglomerates of the hardened material at least once; loading thematerial in a frame and curing again the material by applying aprescribed pressure at a working site for forming a container-likeformed body; and digging a hole at a working site and embedding theformed body in the inside of the hole so as to nurture a plant and/ortree in the formed body. In this case, the container-like formed body ispreferably a planter or the working site is preferably in a desert.

According to the invention, land sliding in a sidewall of a roaddeveloped by cutting out a sloping land or in a quarry can be prevented.Besides heat island phenomenon in urban cities can be suppressed,environments matching with the surrounding of a construction site can beproduced and greening of a desert is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the correlation between a dry density and thewater content of a civil engineering material of the invention;

FIG. 2 shows a road developed by cutting out a sloping land; and

FIG. 3 shows a civil engineering work example in the case of greening ofa desert and FIG. 3(a) shows a case of embedding one formed body in onehole and FIG. 3(b) shows a case of embedding a large number of formedbodies in one hole.

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, the embodiments of the invention will be described withreference to the background of the accomplishment of the invention.

Inventors of the invention at first assumed that if a material haswashing out resistance and good ventilation property,water-permeability, water retention property and thermal conductivity,the material is effective for suppressing heat island phenomenon even ifit does not have planting suitability since water evaporation heat canbe used. The material can be applied, for example, for parking lots incities, malls of public parks, and lower parts of sidewalls of roadsdeveloped by cutting out sloping lands. On the basis of investigationscarried out at the time of invention of the above-mentioned conventionalHosolite, inventors reminded the finding that plantability could bereduced by increasing the secondary generation of strength of ahydraulic material to a certain value after it became hardened by curing(called as the plant growth limit strength, e.g. about 14.0 N/cm²).According to the common knowledge in the civil engineering technology,decreasing the water content in the material, adding no fine powder tothe aggregate, or increasing the amount of cement will increase thesecondary generation of strength. Also, it is supposed possible toutilize the hydration reaction of cement as the principle of developmentof the strength, similarly to the case of the above-mentioned Hosolite,even if the particle size of the aggregate becomes small.

Based on these discussions, inventors have continued with a study byusing portland cement as the cement and a fine powder for the aggregateand adding 20 to 40% by weight of water as extrapolated weight. And itwas found that if 50% by weight or more of aggregate containing a finepowder with 0.1 mm or smaller is used just like the conventionalHosolite, it is difficult to keep the secondary generation of strengthof the material after hardening by curing at the above-mentioned plantgrowth limit value or higher. This is presumably because of excessiveamount of fine powders and water.

Therefore, the study was further continued, by decreasing the amount ofthe fine powder with 0.1 mm or smaller to a range of 10 to less than 50%by weight. It was found that the secondary generation of strength couldreach the plant growth limit or higher even if the water content wasless than 20% by weight. A number of tests were conducted by changing atype of aggregate as it will be described later until it was confirmedthat same results could be obtained in any case to accomplish theinvention. In this case, the secondary generation of strength ismeasured according to Concrete test method of JIS (JIS A1108) using ahydration-aged column test specimen (height: 150 mm and diameter: 50mmφ). The correlation between the water content and the dry density of atest specimen is shown in FIG. 1, and from the value of the dry density,obviously the secondary generation of strength exceeds the plant growthlimit strength. This is because the results shown in FIG. 1 satisfy thestandard according to the restriction related to “Soil tightening andhardening of surplus soil,” stating that if the dry density is 95% orhigher of the maximum dry density value, the material is available forpractical use. However, if the water content is less than 10% by weight,the material becomes same as conventional cement concrete and if thewater content is more than 40% by weight, the solidification becomesinsufficient and the washing out resistance is considerably decreasedand therefore, the amount of water to be extrapolated is defined in arange of 10 to 40% by weight. Further, if the amount of the fineaggregate powder of 0.1 mm or smaller becomes less than 10% by weight,the material becomes just like cement concrete. Therefore the aboveranges were excluded from the present invention.

As the aggregate to be used in the invention, those which properlycontain SiO₂ and CaO effective for pozzolanic reaction can be used andsoil in a work field, incinerator ashes of industrial wastes, and slaggenerated by incineration as well as sand and earth are exemplified. Asthe cement, commercialized cement other than portland cement andso-called self-made ones from granulated blast furnace slag, gypsum,lime, fly ashes may be used.

Inventors have made further investigations as to whether the materialscan be matched with the color in the ambient environments. Accordingly,inventors have found that substances and their powders coloring with thefollowing characteristics may be selected or mixed and the materialsobtained by mixing such substances are also claimed as the invention. Itis because paving with longer-lasting coloration is possible as comparedwith paving colored by spraying a painting material to the surface.

For example, it is effective to use a hematite ore (ferric oxide) forred type coloration, a magnetite ore (ferrous oxide) for black typecoloration, and granulated blast furnace slag. Also, colored artificialstones and artificial coloring materials such as plastics and theircrushed debris can be used for coloration adjustment in a wide range.The addition amounts of these substances may be adjusted in an actualwork field in a try and error manner or as previously planed anddetermined.

Investigation was also conducted on the construction method in a placewhere plantability of the civil engineering material is required to acertain extent. Since the civil engineering material is provided with aheightened secondary generation of strength by sacrificing plantability,it is required to deal with the countermeasure for the sacrifice. As aresult, it is found effective to previously mix seeds of plants and/orfertilizers to the material before the construction and such civilengineering materials are also added to the invention. Also in such acase, the amounts to be added may be adjusted in an actual work field ina try and error manner or as previously planed and determined, similarlyto the case of the above-mentioned coloration.

The above-mentioned construction method of the civil engineeringmaterial of the invention is as follows. At first, cement and aggregatemade ready at the work site or transported from another place are mixedeach other and then water is added to the mixture and the resultingmixture is aged for 8 to 48 hours. After that, the agglomerate hardenedto a certain degree is loosened by manpower or mechanically. If thecuring site and the construction place are different, the obtainedmaterial is transported to the construction place, and sprayed (poured)and properly pressurized and left still for curing again. Accordingly, asolidified body with a secondary generation of strength as desired canbe obtained by properly adjusting the initial curing time and the degreeof the pressure application in the construction place. The reason fordefining the initial curing time in a range of 8 to 48 hours is becauseif it is shorter than 8 hours, the hardness becomes insufficient and ifit is longer than 48 hours, the loosening work becomes difficult.

Since the pressurizing degree depends on the types and amounts of thecement and aggregate to be used, and the amount of extrapolated water,it should be previously determined by carrying out a small-scale test.

In this case, an Eirich mixer, a dump truck, and a bulldozer can be usedpreferably for mixing, transportation, and pressurization, respectively.

Successively, inventors have thought that the civil engineering materialof the invention is useful in a variety of places and have madeinvestigations on the construction method for afforestation. As aresult, the following method is found effective even in water-permeablesoil of such as a desert or the like and the method is also added to theinvention.

At first, as shown in FIG. 3, the above-mentioned civil engineeringmaterial of the invention is mixed, aged for 8 to 48 hours, and thehardened aggregate is loosened at least once and fed to a frame andagain aged under a prescribed pressure to obtain a formed body in acontainer-like form. The reason for that is because if it is tried togrow plants in soil with excessive water permeability, water does notremain in the surrounding of the plants and thus plant growth issuppressed. By using the container made of the above-mentioned materialof the invention having water retain-ability, water is surely retainedso as to grow plant in a planter.

The container-like formed body 1 is embedded in a hole 3 dug out in theconstruction place so as to grow plant 2 and/or tree 2.

In such a manner, if it is formed by a proper pressure, thecontainer-like formed body 1 made of the above-mentioned material can bebroken by the force of the root of the growing plant 2 since it is notfired and therefore not only root grows freely but also the material ismixed with the surrounding soil 4, resulting in improvement of the soil4. Accordingly, it is easy to carry out afforestation in the entireregion only by digging out a hole 3 even in a land, e.g. a desert,having an immense surface area. At that time, as shown in FIG. 3(b), itis efficient to dig the hole 3 with a huge surface area to embed theformed body therein.

In the present invention, the size and the shape of the container-likeformed body 1 is not particularly limited. Because it is important togrow plant and tree 2 in the inside regardless of the shape and size ofthe formed body. Also, at the time of growing plant and tree 2, norestriction is required for the types of the soil 5 filling thecontainer-like formed body 1. What is required is to produce the formedbody by kneading the material containing common soil, sand in a desert,or the same type material as that of the formed body; curing the kneadedmaterial for 8 to 48 hours; and loosening the agglomerate of thehardened material at least once. The same is true for the soil 4 fillingthe gap between the formed body 1 and the hole 3. It is no need to saythat use of the material of the invention is desirable to assure waterretention in the surrounding of plants. In addition to that, withrespect to the soil 4 filling the above-mentioned formed body 1, notonly a single type but also a mixture of several types of soil may beused. It is because the growth of plant and tree 2 can be controlled byadjusting the mixing amounts. Additionally, the construction method hasan advantageous point in that a large quantity of the container-likeformed bodies 1 may be produced in a place remote from the constructionplace and planting work can be made easily by transporting them byvehicles. In other words, planting can be carried out economically withhigh workability.

EXAMPLE 1

A parking lot with a surface area of 90 m² was constructed by using acivil engineering material of the invention. At that time, the groundwas leveled off after the ground was dug shallowly (depth 0.5 m) and thecivil engineering material produced by mixing and stirring water 15% byweight as an extrapolated amount with a mixture containing portlandcement and aggregate containing 30% by weight of a fine powder with aparticle size of 0.1 mm or smaller and curing for 36 hours was laid onthe ground and compacted by a road roller. An Eirich mixer was used formixing cement and adding water.

The construction result was evaluated by sampling a column sample byboring after 21-day curing. The uniaxial compression strength wasmeasured to find the strength as extremely high as 20 N/cm², which issufficient to use the construction site as a parking lot. Also, in orderto investigate the water-permeability and water-retention propertynecessary to suppress the heat island phenomenon, a water permeabilitytest was carried out. As a result, although plantability was sacrificed,the water-permeability and water-retention property were also found assufficient as 5.2×10⁻² cm/sec.

EXAMPLE 2

A mall with a full length of 50 m and a width of 3 m was constructed ina public park by using a civil engineering material of the invention.Also in this case, the ground was leveled after the ground was dugshallowly (depth 0.4 m) and the civil engineering material produced bymixing and stirring water 18% by weight as an extrapolated amount with amixture containing portland cement and aggregate containing 20% byweight of a fine powder with a particle size of 0.1 mm or smaller andcuring for 40 hours was laid on the ground and compacted by a roadroller. For the aggregate, granulated blast furnace slag previouslyadjusted so as to contain 20% by weight of a fine powder with a particlesize of 0.1 mm was used to make the coloration white. An Eirich mixerwas used for mixing cement with the aggregate and adding water.

Similarly as in Example 1, the construction result was evaluated bysampling a column sample by boring after 21-day curing. The uniaxialcompression strength was measured to find the strength as extremely highas 18.2 N/cm², which is sufficient to use the construction site as amall. Also, to investigate the water-permeability and water-retentionproperty necessary to suppress the heat island phenomenon, a waterpermeability test was carried out. As a result, although the plantingsuitability was sacrificed, the water-permeability and water-retentionproperty were also found as sufficient as 8.2×10⁻⁷ cm/sec.

EXAMPLE 3

Since a road cutting out a slope of a mountain was opened, as shown inFIG. 2, an upper part along the finished face (an inclination angle 45°with respect to the horizontal line) was coated with a conventionalHosolite and the lower part of 2 m distance from the road was coatedwith the civil engineering material of the invention. In this case, theconventional Hosolite was produced by extrapolating 30% by weight ofwater to a mixture containing portland cement and aggregate (granulatedblast furnace slag) containing 60% by weight of a fine powder with aparticle size of 0.1 mm or smaller. The civil engineering material ofthe present invention was produced by mixing and stirring water in anextrapolated amount of 18% by weight with a mixture containing portlandcement and aggregate (dug-out soil) containing 40% by weight of a finepowder with a particle size of 0.1 mm or smaller. To match the colorwith the ambient environments, the civil engineering material of theinvention was mixed with a ferric oxide powder in an extrapolatingamount of 4% by weight to intensify the brown color. The constructionwas carried out by compacting these materials along the finished facesby using a backhoe.

Similarly as in Example 1, the construction result was evaluated bysampling a column sample by boring after 21-day curing and measuring theuniaxial compression strength was measured to find the strength asextremely high as 15.1 N/cm², which is sufficient to use the coating forpreventing land-sliding of the slanting ground. Plants had scarcelygrown for 1 year in the lower part of the finished face, which showed nomowing work was needed.

EXAMPLE 4

The ruin with a slanting face (the inclination angle 6°) where debrisflow occurred was turned to be a lawn field by using the civilengineering material. At that time, the civil engineering material wasproduced by adding water in an extrapolated amount of 20% by weight to amixture containing portland cement and aggregate of the debris flowsieved so as to contain 40% by weight of a fine powder with a particlesize of 0.1 mm or smaller and aged at a dew point. After 48 hours, theaged face was once dug out to loosen the agglomerate. Tall fescueKentucky 31, which is a native rice plant of America, was seeded at therate of 4 to 5 seeds/cm² in the mixture of the aggregate and cement.

The growth of the lawn is better as the uniting strength of the soil islower. The root extension is limited more to the surface layer part asthe uniting strength is higher. Depending on the type of plants to begrown, the use amount of cement, the water amount and the aggregateparticle size should be changed.

EXAMPLE 5

Similarly to Example 2, water in an extrapolated amount of 18% by weightwas added to a mixture containing portland cement and aggregatecontaining 20% by weight of a fine powder with 0.1 mm or smallerparticle size. The obtained mixture was agitated and cured for 40 hours.In order to save cost of the cement, granulated blast furnace slag wasused as the aggregate, which had been previously adjusted so as tocontain 18% by weight of the fine powder with 0.1-mm particle size.After the hardened material by curing was loosened into granular stateby a shovel and packed in a column-like frame and pressurized at about4.9×10⁵ Pascal to obtain a column-like formed body 1 with an innerdiameter 150 mmφ and a thickness 40 mm as shown in FIG. 3(a). A hole 3with a diameter 500 mm was dug in sandy land of a sea coast to embed theformed body 1 and plant a nursery plant 2 of palm coconut with a heightof about 0.3 m. The surrounding of the nursery plant 2 was filled withsand and soil 4, which was used for producing the formed body 1, at therate of 4:1 to grow the nursery plant. The gap between the formed body 1and the hole was also filled with the soil 4 used for producing theformed body 1.

As a result, the nursery plant 2 grew successfully to reach as high as0.5 m even after 4 weeks.

As described above, the invention provides a civil engineering material(also called as Hosolite), which contributes to suppression of heatisland phenomenon in urban cities, creates environments matching withthe ambient environments of a construction site, and is useful forgreening of a desert as well as being excellent in washing outresistance and/or planting suitability depending on the objects (orpurposes) of the civil engineering works, and to provide a constructionmethod of the material.

1. A civil engineering material comprising 10 to 40% by weight of theentire material added to a mixture, which comprises: 0.5 to 10.0% byweight of cement; and 90.0 to 99.5% by weight of an aggregate powderincluding 10 to less than 50% by weight of fine powder with 0.1 mm orsmaller in size; wherein the material is kneaded and cured for 8 hoursor more and less than 48 hours forming a hardened material containingagglomerates.
 2. The civil engineering material according to claim 1,wherein one or more of granular iron oxide, granulated blast slag,granular steel refining slag, and granular artificial coloring materialsis mixed with the mixture.
 3. The civil engineering material accordingto claim 1, wherein seeds of plants and/or fertilizers are mixed withthe mixture.
 4. A a method for making a civil engineering materialcomprising the steps of: loosening agglomerates of the civil engineeringamterial of claim 1 at least once; and curing again the material byapplying a prescribed pressure at a working site.
 5. A method for makinga civil engineering material comprising the steps of: loosening theagglomerates of the civil engineering material of claim 1 at least once;loading the material in a frame and curing again the material byapplying a prescribed pressure at a working site for forming acontainer-like formed body; and digging a hole at a working site andembedding the formed body in the inside of the hole; wherein theembedded formed body is structurally capable of retaining water andstructurally capable of being broken by a force of a root of a plantgrowing within the embedded container.
 6. The method for making thecivil engineering material according to claim 5, wherein thecontainer-like formed body is a planter.
 7. The method for making thecivil engineering material according to claim 5, wherein the workingsite is a desert.
 8. The civil engineering material according to claim2, wherein seeds of plants and/or fertilizers are mixed with themixture.
 9. A method for making a civil engineering material comprisingthe steps of: loosening the agglomerates of the civil engineeringmaterial of claim 2 at least once; and curing again the material byapplying a prescribed pressure at a working site.
 10. A method formaking a civil engineering material comprising the steps of; looseningthe agglomerates of the civil engineering material of claim 3 at leastonce; and curing again the material by applying a prescribed pressure ata working site.
 11. A method for making a civil engineering materialcomprising the steps of; loosening the agglomerates of the civilengineering material of claim 2 at least once; loading the material in aframe and curing again the material by applying a prescribed pressure ata working site for forming a container-like formed body; and digging ahole at a working site and embedding the formed body in the inside ofthe hole; wherein the embedded formed body is structurally capable ofretaining water and structurally capable of being broken by a force of aroot of a plant growing within the embedded container.
 12. A method formaking a civil engineering material comprising the steps of; looseningthe agglomerates of the civil engineering material of claim 3 at leastonce; loading the material in a frame and curing again the material byapplying a prescribed pressure at a working site for forming acontainer-like formed body; and digging a hole at a working site andembedding the formed body in the inside of the hole; wherein theembedded formed body is structurally capable of retaining water andstructurally capable of being broken by a force of a root of a plantgrowing within the embedded container.
 13. The method form making thecivil engineering material according to claim 6, wherein the workingsite is a desert.